Ventilation unit

ABSTRACT

A ventilation unit for generating an air flow comprises a centrifugal rotor able to rotate about an axis of rotation, a diffuser comprising a first and a second outlet, the outlets being positioned on opposite sides of the centrifugal rotor and delimiting a blowing duct; the centrifugal rotor is inserted in the blowing duct and is aligned with the first outlet and with the second outlet according to a main axis which is perpendicular to the axis of rotation.

TECHNICAL FIELD

This invention relates to a ventilation unit and in particular a ventilation unit comprising a centrifugal fan, more specifically a radial fan, which is housed in a corresponding diffuser.

BACKGROUND ART

Radial fans are fans of a substantially known type which, when driven to rotate suck air from an intake which is coaxial with the axis of rotation and generate an air flow which is spread radially from the fan itself.

Such fans are usually inserted, together with a respective motor, in diffusers which are suitably shaped for directing and optimising the air flow generated by the fan.

In general the fans described above are used in the automotive sector, for example in cars, lorries, agricultural machinery, earth moving machinery, buses and the like, for carrying heat away from heat exchangers, for moving air in driver and passenger compartments or, in general, for cooling components or parts which are subject to temperature increases during operation.

Recently there has been a particular need, in vehicles powered also or exclusively by electricity, for cooling the energy storage batteries.

In this particular application, prior art fans were developed to obtain low noise emissions accompanied by high fluid dynamic efficiency in relatively limited dimensions, but satisfactory results were not achieved.

DISCLOSURE OF THE INVENTION

In this context, the main aim of this invention is to overcome the above-mentioned disadvantages

One aim of this invention is to provide a ventilation unit, intended in particular for cooling batteries, which is more efficient than the prior art solutions.

A further aim is to provide a ventilation unit which has lower noise emissions than the prior art solutions.

The technical purpose indicated and the aims specified are substantially achieved by a ventilation unit according to claim 1.

BRIEF DESCRIPTION OF DRAWINGS

Further features and advantages of this invention are more apparent from the non-limiting description which follows of a preferred, non-limiting embodiment of a ventilation unit as illustrated in the accompanying drawings, in which:

FIG. 1 is a partly exploded schematic perspective view of a ventilation unit according to this invention;

FIG. 2 is a schematic side view of the ventilation unit of FIG. 1;

FIG. 3 is a cross-section of the ventilation unit according to line III-III of FIG. 2;

FIG. 4 illustrates a fluid dynamic simulation of operation of a ventilation unit according to this invention

FIG. 5 illustrates a second fluid dynamic simulation of operation of a ventilation unit according to this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

With reference to the accompanying drawings, the numeral 1 denotes a ventilation unit according to this invention, which is intended to generate a cooling air flow F.

The ventilation unit 1 comprises a centrifugal rotor 2, in particular radial, having an external diameter D and able to rotate about an axis R of rotation, means for operating the rotor 2, of the substantially known type and schematically illustrated with a block 3, and a diffuser 4 for supporting the rotor 2.

The rotor 2, only described as regards those parts necessary for an understanding of this invention, comprises a hub 2 a and a plurality of vanes 2 b, with tips 2 c, which are connected to the hub 2 a.

The diffuser 4 extends according to a plane P which is perpendicular to the axis R of rotation and delimits a blowing duct 5 in which the rotor 2 is inserted.

The diffuser comprises an inlet 20 and a first and a second outlet 6, 7 for the air flow F.

The first and second outlets 6, 7 are positioned on opposite sides of the rotor 2.

As illustrated, the first and second outlets 6, 7 are positioned on opposite sides of the inlet 20 of the diffuser 4.

The centrifugal rotor 2, the first outlet 6 and the second outlet 7 are aligned with each other according to a main axis X which is perpendicular to the axis R of rotation.

The inlet 20 of the diffuser 4 corresponds, preferably, to an inlet of the rotor 2.

The inlet 20 of the diffuser 4 extends in a plane transversal to, preferably perpendicular to, the axis R of rotation.

The axis X also defines a blowing direction of the ventilation unit 1 which, in the example illustrated, corresponds to the main direction of extension of the diffuser 4.

The axis R of rotation defines a preferred flow direction of the air entering the rotor 2 and the diffuser 4.

The air flow F exits the duct 5 along the blowing line in a direction V1 from the outlet 6 and exits in a direction V2, opposite to V1 from the outlet 7.

In other words, the diffuser 4 and the rotor 2 are assembled and configured relative to each other in such a way that the flow generated by the rotor 2 is distributed in the directions V1 and V2 of the blowing line parallel with the main axis X.

The diffuser 4 advantageously has a structure with central symmetry, the centre being at the axis R of rotation.

In other words, considering a section parallel with the plane P, perpendicular to the axis R, the axis R itself defines at the intersection with the above-mentioned section the centre of symmetry of the section considered.

In that way, the flow F remains divided in a balanced way in terms of flow rate between the two outlets 6, 7.

In the example illustrated the diffuser 4 has the shape of a parallelepiped, in particular a right-angled parallelepiped, comprising an upper face 8, a lower face 9, a first and a second side face 10, 11 while the outlets 6, 7 define the remaining two faces of the diffuser 4.

The first and second outlets 6, 7 respectively delimit a first and a second outfeed section 6 a, 7 a for the flow F.

In the embodiment described by way of example, the inlet 20 of the diffuser 4 is provided on the face 8.

The first and second outfeed sections 6 a, 7 a are transversal to the axis X and in particular are perpendicular to it.

Moreover, preferably, the first and second outlets 6, 7 are positioned at the same height, measured along the axis R of rotation.

Preferably, the outlets 6, 7 are identical and are positioned symmetrically relative to the rotor 2.

Looking at the rotor 2 in more detail, it may be seen how advantageously the height of the rotor, measured along the axis R, is comparable with the height of the duct 5, measured along the axis R.

With reference in particular to FIGS. 3, 4 and 5, it can be seen how the rotor 2 is of the radial type with vanes 2 b having tips 2 c pointing backwards. In that case, in the figures indicated, the direction V3 of rotation is anti-clockwise.

in the solution illustrated in FIGS. 1, 2, 3 and 5, the diffuser 4 comprises means for guiding the above-mentioned air flow F inside the duct 5.

The flow guide means are positioned in the diffuser between the rotor 2 and the first outlet 6 and between the rotor 2 and the second outlet 7, for guiding the flow F inside the duct 5.

More precisely, in the example embodiment illustrated, the guide means comprise a first flow diverter 12, positioned in the blowing duct 5 between the rotor 2 and the first outlet 6, which delimits a narrowing 13 in the duct 5.

The guide means also comprise a second flow diverter 14, positioned in the blowing duct 5 between the rotor 2 and the second outlet 7, which delimits a second narrowing 15 in the duct 5.

The first flow diverter 12 and the corresponding narrowing 13 and the second flow diverter 12 with the corresponding narrowing 14 are positioned on opposite sides of the rotor 2 along the axis X.

The first flow diverter 12 and the corresponding narrowing 13 and the second flow diverter 14 with the corresponding narrowing 15 are positioned on opposite sides of the rotor 2 along a transversal axis Y which is perpendicular to the blowing line and to the axis R of rotation.

The axis R of rotation, the main axis X and the transversal axis Y define a set of three axes which are at tight angles to each other.

Preferably, the diffuser 4 has a structure with central symmetry, the centre being at the axis R of rotation.

In other words, considering a section parallel with the plane P, perpendicular to the axis R, the axis R itself defines at the intersection with the above-mentioned section the centre of symmetry of the section considered.

As illustrated, since the rotor 2 is of the radial type with vanes having tips pointing backwards and able to rotate in an anti-clockwise direction V3 in the example figures, the first flow diverter 12 and the second flow diverter 14 are positioned in the duct 5 in such a way that, in practice, given a vane 2 b the tip 2 c of the vane encounters, during air flow F generation, first the first flow diverter 12 followed by the second narrowing 15, then the second flow diverter 14 and finally, before encountering the first flow diverter 12 again, it encounters the first narrowing 13.

In that way, as is described in more detail below, the flow F is optimised in terms of noise and efficiency.

In the example illustrated, the first and second side faces 10, 11 of the diffuser 4, that is to say, the walls which define them, are shaped in such a way as to create, inside the duct 5, the flow diverters 12 and 14 which project towards the inside of the duct 5.

In further embodiments, the faces 10, 11 are fiat and the flow diverters 12, 14 project from them towards the inside of the duct 5.

Again in this embodiment, equipped with flow diverters 12. 14 for guiding the flow F, as indicated the diffuser 4 maintains a central symmetry, the centre being at the axis R of rotation.

The first and second flow diverters 12, 14 have a similar shape and profile and each comprises a respective first face 12 a, 14 a which is curved, with the concavity facing towards the rotor 2.

Its first face 12 a, 14 a is formed by a portion of a cylindrical surface whose main axis coincides with the axis R of rotation.

Advantageously, as also illustrated in FIG. 5, the faces 12 a, 14 a, which are defined by a portion of cylindrical surface, convey the flow exiting the rotor 2 towards the outlets 7 and 6, following its natural rotational pattern.

In that way, the diffuser 4 is particularly efficient in conveying the flow F exiting the rotor 2 towards the outlets 7 and 6.

Preferably, the faces 12 a, 14 a extend towards the outlet 7 and the outlet 6, respectively, with a stretch or profile 12 d, 14 d.

The stretches 12 d and 14 d are each preferably defined by a flat surface lying in the plane defined by the axes R and X.

The first and second flow diverters 12, 14 each have a respective second face 12 b, 14 b which is curved, with the concavity respectively facing towards the first outlet 6 and towards the second outlet 7.

The first and second flow diverters 12, 14 each have a cusp, that is to say, a rounded point, 12 c, 14 c, connecting the first face 12 a, 14 a and the second face 12 b, 14 b.

Given the diameter “D” of the rotor 2 and the width “H” of the duct 5 (measured along the axis Y), starting from the corresponding wall of the diffuser 4 the height “h”, measured along the axis Y, of the cusps 12 c and 14 c is a function of “H” and “D”, that is to say, h=□(H;D).

Similarly, the distance “I” of the cusps 12 c, 14 c from the axis R of rotation, measured along the axis X, is a function of “H” and “D”, that is to say, I=□(H;D).

The functions of “H” and “D” indicated above are also weighted based on the rotor 2 speed of rotation.

The guide means 12, 14 allow the recovery of dissipated energy which would otherwise be lost in the generation of vortices.

In FIG. 4, showing the basic embodiment of the diffuser 4, the numeral 16 denotes recirculations in the flow F.

FIG. 5 shows how the recirculations are absent in the embodiment of the ventilation unit 1 comprising the flow diverters 12, 14, under the same operating conditions.

Advantageously, the presence of the flow diverters 12, 14 causes an increase in performance, even compared with the first embodiment illustrated in FIG. 4, without compromising the output flow rate from the ventilation unit 1. Moreover, the flow F remains divided in a balanced way in terms of flow rate between the two outlets 6, 7.

Advantageously, elimination of the recirculations 16 contributes to a reduction in the overall noise of the ventilation unit 1.

In general, the central symmetry of the ventilation unit 1 allows the flow F to be rendered uniform in all portions of the diffuser 4.

As indicated, the positioning of the flow diverters 12, 14 in the duct 5 is determined depending on the dimensions of the rotor 2 and the speed of rotation of the rotor.

The position “I” according to the axis X of the flow diverters 12, 14 depends on the flow rate and the speed of rotation of the rotor 2, like the height “h” of the flow diverters relative to the corresponding wall of the diffuser. 

1. A ventilation unit for generating an air flow comprising a centrifugal rotor able to rotate about an axis of rotation, a diffuser associated with the centrifugal rotor, comprising a first and a second outlet, the outlets being positioned on opposite sides of the centrifugal rotor and delimiting a flow blowing duct, the centrifugal rotor being inserted in the blowing duct, said ventilation unit being characterised in that the centrifugal rotor, the first outlet and the second outlet are aligned with each other according to a main axis which is perpendicular to the axis of rotation.
 2. The ventilation unit according to claim 1, wherein the diffuser comprises means for guiding the air flow in the blowing duct, said guide means operating between the centrifugal rotor and the first outlet and/or between the centrifugal rotor and the second outlet.
 3. The ventilation unit according to claim 2, wherein the guide means comprise a first flow diverter, forming a first narrowing in the duct, positioned in said blowing duct between the rotor and the first outlet, and a second flow diverter forming a second narrowing in the duct and positioned in the blowing duct between the rotor and the second outlet, said first and second flow diverters being positioned on opposite sides of the rotor.
 4. The ventilation unit according to claim 3, wherein the first and second flow diverters each have a first face which is curved, with the concavity facing towards the rotor.
 5. The ventilation unit according to claim 4, wherein the first face of the first and second flow diverters is formed by a portion of a cylindrical surface having a main axis which coincides with the axis of rotation.
 6. The ventilation unit according to claim 3, wherein the first and second flow diverters each comprise a second face which is curved, with the concavity respectively facing towards the first outlet and towards the second outlet, and a cusp connecting the first face and the second face.
 7. The ventilation unit according to claim 3, wherein the rotor is of the radial type with vanes having tips pointing backwards, said first and second flow diverters being positioned in the blowing duct in such a way that during generation of the air flow said tips encounter, one after another, the first flow diverter, the second narrowing, the second flow diverter and the first narrowing.
 8. The ventilation unit according to claim 1, wherein the diffuser has a central symmetry, the centre of symmetry belonging to the axis of rotation. 